Eutectic Die Attach

Eutectic die attach is a highly controlled die attach process for high reliability, high accuracy requirement devices. To achieve high yield, sophisticated heating and cooling mechanisms are employed. This includes software that heats and cools according to a very strict parameter line.

The essence of a eutectic reaction is going from liquid to solid, bypassing the plastic state, using eutectic heating and cooling. Eutectic alloys for soldering are composed of Sn (tin), Pb (lead), Ag (silver) and Au (gold). When different metals are combined into alloys, a range of melting temperatures are created with varying proportions of each metal used: AuSi@363°C, AuSn@280°C.

During eutectic die attach, the substrate is heating to a temperature just below the solder's eutectic temperature. During the bond cycle, an incremental thermal energy is supplied to the solder layer to promote the solder melting process. Liquified solder then penetrates both bonding surfaces. The result is an intermetallic bond (also known as wetting) develops.